Generally, a process cartridge detachably mounted in an electrophotographic image forming apparatus includes at least a toner frame. The toner frame contains a developer and a developing member that carries the developer. The electrophotographic image forming apparatus includes a printer, a duplicating machine, and the like. Hereinafter, a printer is used for description. In a working process of the printer, a photosensitive member for forming an electrostatic latent image is generally disposed separately in the printer, or disposed together with the developing member in the toner frame, or disposed separately in a waste toner frame used for containing a waste developer, where the waste toner frame is combined with the toner frame to constitute the process cartridge.
An image forming process of the printer generally includes steps of charging, exposure, developing, transfer, fixing, and cleaning. First, a charging member disposed in the printer or process cartridge charges the surface of the photosensitive member. After being charged, the photosensitive member is exposed by the laser beams which include digital image signals in the printer, and thereby an electrostatic latent image is formed on the surface of the photosensitive member. The electrostatic latent image is developed by the developing member that carries the developer. Then a transfer apparatus transfers the image to a recording medium, and a fixing apparatus heats the image and presses the image to the recording medium. The printer outputs the recording medium. Finally, a cleaning apparatus cleans the photosensitive member, and thereby the image forming process is completed.
According to whether the developing member contacts the photosensitive member when the printer works, developing methods may be classified into a contact-type developing method and a jump-type developing method. In the contact-type developing method, the developing member and the photosensitive member contact with each other, the printer applies a DC bias voltage to the developing member to form an electric field between the developing member and the photosensitive member, the developer located on the developing member is moved from the surface of the developing member to the surface of the photosensitive member under the action of the electric field, and thereby an said electrostatic latent image is developed. In the jump-type developing method, the developing member and the photosensitive member do not contact with each other but have a predetermined gap, and the printer applies a voltage after superimposition of a DC bias voltage and an AC bias voltage to the developing member; however, in the developing process, the AC bias voltage plays a major role, the developer located on the developing member jumps over the gap from the surface of the developing member to the surface of the photosensitive member under the action of an AC electric field, and thereby an electrostatic latent image is also developed.
FIG. 1 is a schematic diagram of an overall structure of a process cartridge C01 (hereinafter “process cartridge C01” for short) using the contact-type developing method in the prior art. FIG. 2 is a cross-section diagram of an A-A section in FIG. 1. As shown in FIG. 1, the process cartridge C01 includes a toner frame 10 and a waste toner frame 20 that are combined with each other, and a conductive end cover E and a drive end cover F that are respectively located at a conductive end and a drive end in the toner frame. As shown in FIG. 2, the toner frame 10 includes a developer container 11, a stirring member 12, a developer transmission member 13, a developing member 14, a photosensitive member 15, a developer layer adjusting member 16, and a sealing member 17. The stirring member 12 is rotatably disposed in the developer container 11, and configured to stir the developer and provide the developer to the developer transmission member 13. The developer transmission member 13, developing member 14, and photosensitive member 15 are supported by the conductive end cover E and drive end cover F, and sequentially mounted in contact in the toner frame 10. The developer transmission member 13 is configured to transmit the developer to the developing member 14, and a redundant developer on the developing member 14 is adjusted by the developer layer adjusting member 16; meanwhile, the developer is frictionized, so that the developer is charged. The sealing member 17 is used for sealing in a longitudinal direction of the developing member 14. The waste toner frame 20 includes a waste developer container 21, a charging member 22, and a cleaning member 23. The charging member 22 is configured to charge the surface of the photosensitive member 15 before development. The cleaning member 23 is configured to clean a residual developer on the photosensitive member 15 after development. For ease of holding the process cartridge C01, the process cartridge C01 further includes a handle 24 disposed on the waste toner frame 20.
FIG. 3 is a cross-section diagram of a process cartridge C02 (hereinafter “process cartridge C02” for short) using the jump-type developing method in the prior art. A structure of the process cartridge C02 is approximately the same as that of the foregoing process cartridge C01, and same numbers are used for same components in the two process cartridges. The process cartridge C02 differs from the process cartridge C01 in that a gap g is reserved between the developing member 14 and the photosensitive member 15. Therefore, to ensure that the developer can jump over the gap from the surface of the developing member 14 to the surface of the photosensitive member 15, a developing voltage applied to the process cartridge C02 by a printer to which the process cartridge C02 is applicable is a voltage after superimposition of a DC bias voltage and an AC bias voltage.